نوع مقاله : مقالات پژوهشی
گروه تولید و ژنتیک گیاهی دانشکده کشاورزی دانشگاه شیراز
عنوان مقاله [English]
Introduction: Quinoa (Chenopodium quinoa L.) is a highly nutritional seed crop from the Andean region with huge genetic variability, enabling its cultivation across a wide range of environmental conditions. The area and production under quinoa in the world in 2020 was 189000 ha with 175000 tonnes production. There is some evidence for allelopathic activity of quinoa and this potential could be probably used in terms of integrated weed management. Agronomic practices such as nitrogen fertilization influence weed emergence, growth and competition in a crop. Nevertheless, despite the numerous studies on new and promising crops globally, there is a clear lack of information on the combined effect of weed density and nitrogen fertilizer sources on quinoa crop. Therefore, the purpose of this study was to evaluate the effects of nitrogen fertilizer sources and red root pigweed densities on growth, yield and competitive ability of quinoa (Chenopodium quinoa Willd). This information could be helpful for the overall development of crop and weed management strategies in quinoa crop.
Materials and Methods: In order to evaluate the effect of nitrogen fertilizer sources on growth, yield and competitive ability of quinoa in red root pigweed densities, a field study carried out during 2021 growing season in research farm of School of Agriculture, Shiraz University. The experiment was conducted in a split-plot based on a randomized complete block design with 3 replications. Nitrogen fertilizer sources (control, urea, sulfur coated urea and ammonium nitrate) were assigned to main plots and density of red root pigweed at 6 levels (0, 5, 10, 15, 20 and 25 plants m-2) to the sub-plots. The 2-meter square from each plot were harvested to determine quinoa traits, as well as weed traits. The quinoa traits included plant height, leaf area index, number of grain per plant, 1000 grain weight, grain yield, biological yield and harvest index. Plants were oven-dried at 75 C for 72 h to determine seed yield. Weeds were harvested from a 2 m2 area in each plot to determine plant height, shoot height, panicle length and leaf area index. Data were analyzed using SAS v. 9.1 software (SAS Institute 2003). When significant differences were observed among treatments, mean comparisons were made using Duncan's multiple range tests (P < 0.05).
Results and Discussion: Results showed that the application of sulfur coated urea could enhance competitive ability of quinoa. The results of the experiment showed that weed density decreased plant height, leaf area index, number of grain per plant, 1000 grain weight, grain yield, biological yield and harvest index. The application of sulfur coated urea in most cases improved the effects of weed density; i.e., application of sulfur coated urea in the highest weed density (25 plant m-2) increased plant height by 1.1 times, leaf area index by 2.5 times, number of grain per plant by 2.5 times, 1000 grain weight by 1.1 times, grain yield by 2.8 times, and biological yield by 1.8 times compared with control. At 0, 5, 10, 15, 20 and 25 plant m-2 red root pigweed densities, sulfur coated urea increased number of grain per plant by 86.5, 118, 139.4, 168.8, 149.6 and 153.4% 1000 grain weight by 7.9, 7.9, 9.8, 9.9 and 9.9% and ability to withstand competition by 19.6, 31.9, 55.0, 42.7 and 37.8% compared with control. In the present study, sulfur coated urea caused an increase in growth, yield and ability to withstand competition of quinoa compared to the control. These results are similar to those of who found that the application of organic nutrients reduce weed competition in cropping systems. Furthermore, it has been demonstrated that weeds produce greater biomass with the application of fertilizer compared to the control. Therefore, it can be concluded that the increased grain yield of quinoa induced by sulfur coated urea was due to the improve of ability to withstand competition.
Conclusion: The application of sulfur coated urea led to a higher quinoa yield compared to using control. However, weed competition was greater with urea fertilization in comparison with sulfur coated urea fertilizer. In addition, most weeds are highly responsive to soil N, so the application of all fertilizer types should be carefully considered to reduce the competitive advantage of weeds over crops.
Acknowledgements: We would like to thank the School of Agriculture, Shiraz University for their support, cooperation, and assistance throughout this research.
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